In order to clarify the clinicopathological aspects of Moyamoya disease (spontanecus occlusion of circulus arteriosus Willisi), the conditions causing the abnormal cerebral vascular networks (Moyamoya vessels) were studied by means of cerebral angiography, computed tomography and clinical findings.
1) The cerebral juxtabasal vascular networks seemed to be the parenchymal vessels such as medial and lateral striate arteries, thalamoperforating, thalamogeniculate, anterior mamillary, anterior and posterior choroidal arteries etc., which became dilated and tortuous as collateral anastomoses caused by occlusion of carotid forks. Occlusion of the proximal internal carotid artery preserved circulation of A1, M1 and anterior communicating artery did not cause the cerebral juxtabasal vascular networks.
2) Leptomeningeal anastomoses and transdural cortical anastomoses seemed to be caused by occlusion of any portion of internal carotid artery.
3) Cerebral ischemic syndrome and cerebral infarction may result from insufficient collateral circulation, which may be observed in the borderland between two collaterals. Various distributions of collateral circulation may result in the varicus aspects of cerebral infarction or cerebral atrophy in this disease.
